Synthesis Of Dual-Channel Excited Rare-earth Upconversion Nanoparticles For Luminescence Imaging

The influence of rare-earth elements on plants and crops is more and more concerned,and the existing analysis method for rare-earth elements is the traditional analysis,such as ICP-MS.In order to observe migration and accumulation rule of the rare earth elements in plant in vivo,we need to develop a new methods.Rare-earth upconverting luminescent nanophosphors as a new type of luminescent materials have advantages of high chemical stability,optical stability and excellent optical penetrability,so that it is suitable for application in biological fluorescence imaging.In this thesis,dual-channel excited rare-earth upconversion nanoparticles as core/shell nanostructures were designed and synthesized.The nanoparticles can emit upconverting luminescence under excitation at 980 nm and 808 nm.Then upconverting luminescent nanoparticles were used to study the fluorescence labeling and imaging in animals and plants.1.Synthesis and characterization of dual-channel rare-earth upconversion nanoparticlesMulti-layer core-shell structure of dual-channel excited rare-earth upconversion nanoparticles NaYbF₄:Tm³⁺@NaYF₄:Yb³⁺@NaYbF₄:Nd³⁺@NaYF₄:Yb³⁺?CSSS?which can be under excitation at 980 nm and 808 nm were synthesized by high-temperature cracking.In addition,we synthesized acore-shellstructureofrare-earthupconversionnanoparticles NaYF₄:Yb³⁺,Nd³⁺,Tm³⁺,Er³⁺@NaYF₄:Nd³⁺?CS-Nd?,and the surface morphology,fluorescence spectroscopy,surface ligand group of nanoparticle CS-Nd were characterized by TEM,SEM,FT-IR.The results show that the core/shell rare-earth luminescence nanoparticles CS-Nd can emit upconverting luminescence under excitation at 980 nm and 808 nm.2.Synthesis and biological imaging application of water-soluble rare-earth upconverting luminescent nanophosphorsThe water-soluble for nanoparticles?CS-Nd-cit?was modified with citric acid by ligand exchange method.The nanoparticles morphology and surface functional groups was tested by TEM and FT-IR.The results confirmed that the hydrophilic group on CS-Nd-cit surface increased,and water soluble modified for CS-Nd-cit could be achieved.Secondly,the CS-Nd-cit were used for cell imaging fluorescent labeling studies,the experimental results show that CS-Nd-cit can effectively achieve the cell fluorescence imaging.And then,CS-Nd-cit was used for mice in vivo fluorescence labeling,the results show that CS-Nd-cit can realize in vivo fluorescence imaging under excitation at 808 nm.3.Biological fluorescence imaging of water-soluble rare-earth upconverting luminescent nanophosphors in arabidopsisThe biodistribution imaging of CS-Nd-cit nanoparticles in arabidopsis thaliana were studied.Arabidopsis hydroponic experiment results show that in a certain time,CS-Nd-cit in the roots,stems and leaves of arabidopsis cannot be detected.Then,we designed arabidopsis foliar spraying CS-Nd-cit experiments,the confocal fluorescence imaging data shows that as incubation time increased to several days,the fluorescence signal of CS-Nd-cit in rabidopsis foliage was observed.Furthermore,through the whole blade fluorescence imaging observation,this confirmed that the blade contains nanoparticles CS-Nd-cit.